Éditeur(s) : Taylor & Francis Ltd
Résumé : A new benthic phototrophic dinoflagellate is described from sediments of a tropical marine cove at Martinique Island and its micromorphology is studied by means of light and electron microscopy. The cell contains small golden-brown chloroplasts and the oval nucleus is posterior. It is laterally compressed, almost circular in shape when viewed laterally. It consists of a small epitheca tilted toward the right lateral side and a larger hypotheca. In the left view, the cingulum is more anterior and the epitheca is reduced. The cingulum is displaced and left-handed. This organism is peculiar in having no apical pore and its thecal plate arrangement is 2 ' 1a 7 '' 5c 3s 5 ''' 1 ''''. The plates are smooth with small groups of pores scattered on their surface. An area with 60-80 densely arranged pores is found near the centre of the 2 ''' plate, on the left lateral side. Morphologically, these features are different from all other laterally compressed benthic genera. In addition, molecular genetic sequences of SSU and partial LSU form a distinct and well-supported clade among dinoflagellates and support the erection of a new genus. However, molecular phylogenies inferred from ribosomal genes failed to confirm any clear relationship with other benthic taxa and affinity with other laterally compressed dinoflagellates has not been demonstrated. Hence, the taxonomic affinity of Madanidinium loirii with a defined order and family is unclear at the moment.
European Journal Of Phycology (0967-0262) (Taylor & Francis Ltd), 2014-04 , Vol. 49 , N. 2 , P. 165-178

Droits : 2014 British Phycological Society
http://archimer.ifremer.fr/doc/00195/30622/29458.pdf
DOI:10.1080/09670262.2014.898797
http://archimer.ifremer.fr/doc/00195/30622/

Éditeur(s) : HAL CCSD Wiley-Blackwell
Résumé : International audience
Although protists are critical components of marine ecosystems, they are still poorly characterized. Here we analysed the taxonomic diversity of planktonic and benthic protist communities collected in six distant European coastal sites. Environmental deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from three size fractions (pico-, nano- and micro/mesoplankton), as well as from dissolved DNA and surface sediments were used as templates for tag pyrosequencing of the V4 region of the 18S ribosomal DNA. Beta-diversity analyses split the protist community structure into three main clusters: picoplankton-nanoplankton-dissolved DNA, micro/mesoplankton and sediments. Within each cluster, protist communities from the same site and time clustered together, while communities from the same site but different seasons were unrelated. Both DNA and RNA-based surveys provided similar relative abundances for most class-level taxonomic groups. Yet, particular groups were overrepresented in one of the two templates, such as marine alveolates (MALV)-I and MALV-II that were much more abundant in DNA surveys. Overall, the groups displaying the highest relative contribution were Dinophyceae, Diatomea, Ciliophora and Acantharia. Also, well represented were Mamiellophyceae, Cryptomonadales, marine alveolates and marine stramenopiles in the picoplankton, and Monadofilosa and basal Fungi in sediments. Our extensive and systematic sequencing of geographically separated sites provides the most comprehensive molecular description of coastal marine protist diversity to date.
ISSN: 1462-2912

hal-01191731
http://hal.upmc.fr/hal-01191731
http://hal.upmc.fr/hal-01191731/document
http://hal.upmc.fr/hal-01191731/file/Massana_2015_Marine_protist.pdf
DOI : 10.1111/1462-2920.12955

Éditeur(s) : Taylor and Francis
Résumé : A new sand-dwelling dinoflagellate species, Cabra reticulata sp. nov., is described from sandy habitats in the south of Brittany (northwestern France). This new species possesses the characteristics of the 'unusual' genus, Cabra Murray et Patterson. The thecal plate formula is Po Pt 3' 1a 4'' 'x' 3c ?s 5''' 1'''' (or alternatively interpreted as Po Pt 4' 0a 4'' 'x' 3c ?s 5''' 1''''). Because of the strong lateral compression, cells of C. reticulata are frequently seen laterally and have a polygonal shape, with three prominent antapical pointed flanges and a dorsal spine in the anterior part of the hypotheca. The cingulum is ascending and incomplete. The thecal surface is ornamented with strong reticulations forming polygonal areolae, which differs from C. matta Murray et Patterson, the type species of the genus. In addition to their different size and shape, a detailed study of C. reticulata by scanning electron microscopy also revealed several different plate features. Plates of the cingulum, c1 and c3, have no reticulations and are ornamented with shallow round areolae, while c2 is only faintly reticulated. Plate 1'''' is also characteristic because dorsally it forms a prominent pointed flange and ventrally bears a peculiar small area of densely arranged pores or tiny areolae. A similar finding has previously been described in Roscoffia capitata Balech. In the description of the genus, it was suggested that Cabra is closely related to species of the genus Roscoffia, and our observations strengthen this hypothesis. Prior to this study, C. reticulata was probably observed in the Virgin Islands, Caribbean Sea, but was tentatively identified as Thecadinium sp. and not fully described. Thus, C. reticulata appears to be present on both sides of the Atlantic Ocean and to occupy benthic habitats in temperate and tropical areas.
European journal of phycology (0967-0262) (Taylor and Francis), 2009-08 , Vol. 44 , N. 3 , P. 415-423

Droits : 2009 Informa plc, Taylor & Francis
http://archimer.ifremer.fr/doc/2009/publication-6804.pdf
DOI:10.1080/09670260902883271
http://archimer.ifremer.fr/doc/00000/6804/

Éditeur(s) : Walter De Gruyter & Co
Résumé : The section of the Liguro-Provencal basin north of the Balearic Islands is one of the most productive sites in the whole Mediterranean Sea, with intense phytoplankton bloom lasting about 2 months in late winter-early spring. The phytoplankton species composition of the area was investigated using light and electron microscopy to analyze bottle and net samples collected at several stations in spring 2000 and 2003. Serial dilution cultures established from bottle samples were also examined. A total of 168 phytoplankton taxa was identified, consisting of 73 Coscinodiscophyceae, 47 Dinophyceae, 25 Coccolithophyceae and 4 Prymnesiophyceae, 5 Prasinophyceae, 3 Chrysophyceae, 2 Cryptophyceae, 2 Dictyochophyceae, 1 Euglenophyceae, 1 Pelagophyceae, 1 Choanoflagellidea, 1 Filosea and 3 incertae sedis. We also provided a brief taxonomic description and original micrographs for 25 of the smallest and/or less known species identified in the study area, which may go undetected during routine microscopical analysis of fixed samples. Among these, 10 species were recorded for the first time in the Mediterranean Sea, confirming the need of detailed studies to reveal the biodiversity and biogeography of Mediterranean phytoplankton.
Botanica Marina (0006-8055) (Walter De Gruyter & Co), 2011-06 , Vol. 54 , N. 3 , P. 243-267

Droits : 2011 by Walter de Gruyter
http://archimer.ifremer.fr/doc/00038/14916/12245.pdf
DOI:10.1515/BOT.2011.033
http://archimer.ifremer.fr/doc/00038/14916/